枇杷果实采后衰老与冷害过程乙烯信号转导元件基因表达调控

项目名称： 枇杷果实采后衰老与冷害过程乙烯信号转导元件基因表达调控

项目编号： No.30871759

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 李鲜

作者单位： 浙江大学

项目金额： 35万元

中文摘要： 项目开展了枇杷果实采后衰老与冷害进程中乙烯信号转导元件基因的表达研究，探索了乙烯信号转导在非跃变型果实中的生物学调控途径。结果表明： 枇杷衰老与冷敏性因品种而异，'洛阳青'（LYQ）易发生衰老/冷害木质化，而'白沙'（BS）在两种情况下均不易发生木质化。从LYQ中克隆得到3个EjETRs，1个EjCTR1，1个EjEIL1和4个EjERFs，它们在不同组织和发育阶段广泛表达。 枇杷成熟衰老过程中，外源乙烯（100 μl-1）可诱导EjERS1a、EjERS1b、EjCTR1、EjERF2和EjERF3的基因表达，表明乙烯可通过信号转导调控果实成熟进程。 LTC和1-MCP（5 μl-1）处理均能减轻LYQ冷害木质化，但机制不同：LTC通过调控EjEIL1基因表达来减轻冷害，而1-MCP通过调控EjETR1转录丰度来减轻冷害，进一步表明EjEIL1可能直接响应低温逆境，而EjETR1可能直接响应乙烯。LTC处理减轻冷害木质化的效果优于1-MCP处理，表明EjEIL1可能是更重要的一个调控位点。 研究结果丰富了乙烯作用的生物学理论，也为完善果实贮运体系提供了科技支撑。

中文关键词： 枇杷；衰老；冷害；乙烯信号转导；基因表达

英文摘要： The present project is focused on the study of expression and regulation of genes associated with ethylene signalling pathway in ripening or chilling injuried loquat (Eriobotrya japonica Lindl.) fruit. The role ethylene signal plays on the biological regulation of non-climacteric fruit was discussed. Main results include: Different loquat cultivars showed different texture changes and chilling sensitivities during postharvest storage. Flesh lignification occurs as a ripening character in 'Luoyangqing' (LYQ) fruit during its postharvest storage at 20℃or as a chilling injury (CI) symptom at 0℃ In 'Baisha' (BS) cultivar, however, no apparemnt fruit lignification was observed during the postharvest storage. Three ethylene receptor genes, one EjCTR1 gene, one EjEIL1 gene, and four EjERFs were isolated and characterized in ripening loquat fruit. All of these genes were expressed in all tissues and fruit at different developmental stages tested. During loquat fruit ripening, all nine genes showed constant or decreased expression patterns in reponse to low level of endogenous ethylene. However, transcripts of EjERS1a, EjERS1b, EjCTR1, EjERF2 and EjERF3 were significantly induced by exogenous ethylene, indicating that external ethylene can stimulate non-climacteric fruit ripening through ethylene signalling. Both LTC and 1-MCP treatments can alleviate chilling-induced lignification, however, their mechanism may be different: LTC may alleviate CI through the regulation of EjEIL1 while 1-MCP may alleviate CI through the regulation of EjETR1 at the transcriptional level. These results further indicate that EjEIL1 may directly respond to low temperature, while EjETR1 may directly respond to ethylene. Furthermore, the effect of CI alleviation was better with LTC treatment than that with 1-MCP treatment, suggesting EjEIL1 might be a more important regulation site for CI prevention in LYQ fruit. Such result may provide a better understanding of the biological roles that ethylene plays on non-climacteric as well as provide technical support for improving the storage and transportation system of loquat and enhancing its international competition.

英文关键词： Loquat; Ripening; Chilling injury; Ethylene signal transduction; Gene expression